Colonoscopy is a medical procedure whereby a fiber optic instrument is introduced into the rectum and advanced into the colon (i.e., large intestine) for detailed examination of the colonic surface. The procedure is performed to diagnose and treat various conditions of the colon. It is the standard screening procedure for colon cancer, the second most common cause of cancer-related death in the U.S. and Canada. Colonoscopy is also performed for a variety of other reasons including investigating gastrointestinal and rectal bleeding, abdominal pain, change in bowel habits, or anemia; to diagnose inflammatory bowel disease; and to further evaluate abnormal gastrointestinal signs and symptoms.
Residual stool in the colon interferes with the quality of the screening, because the stool coats and covers the interior surface of the colon and thus impedes optimal visualization. In order to remove stool from the colon, the patient is normally directed to consume one or more laxatives the day before a colonoscopy, which essentially act as “purgatives.”
Despite these efforts to clean the colon, a good percentage of patients still have stool residue and secretions left behind in the colon. These residual stool contents fill the colonic lumen and coat its surface, thus decreasing the quality of visualization and hence examination of the colon. Studies using large databases reveal that up to 23% of all colonoscopies are associated with suboptimal bowel cleansing and preparation. Suboptimal bowel preparation may decrease the frequency of complete examinations (i.e., advancing the instrument all the way to the cecum and visualizing the appendiceal opening) and may also increase the risk of complications, including increased time required to perform a colonoscopy, discomfort associated with the procedure, decreased detection rate of colon polyps, and in particular decreased detection of “flat lesions” and colon cancer. Suboptimal bowel preparation may also result in decreased time interval between screenings due to concerns about missed lesions.
When a gastroenterologist performs a colonoscopy, he/she is often faced with the following situation. Once the instrument has been introduced into the colon and the examination is in progress, the examiner encounters from a small to a large amount of stool and/or secretions in the colon. A diligent examiner may try to flush normal saline or water into the colon via the “working channel” of the colonoscope and clean the colon as much as possible to increase the quality of visualization. Cleaning the colon during each procedure can become time consuming. Due to the large volume of colonoscopies, an average gastroenterologist is usually very busy, typically performing several colonoscopies in a day. Time consuming, repetitive cleaning procedures can reduce the number of patients that undergo a colonoscopy in a given day.